Small colorless and transparent tremolite crystals are very rare, and cut gems are true collector items. The largest of these is in the 5-10 carat range. Larger crystals exist but are usually badly fractured. Hexagonite is known in facetable material only from New York and these pieces yield gems to only about carat. Chrome tremolite is also very rare and cut gems are tiny. Catseye hexagonites have also been cut. Private Collection: 1.21 (medium purple, New York). National Museums of Canada (Ottawa, Ontario): 1.39 (deep purple, New York); 4.55 (dark blue catseye, Ontario); 12.55 (dark brown catseye, Ontario).

Comments

It is possible to misidentify tremolite, mistaking it for other amphiboles. Hexagonite is the rarest of the gem varieties of tremolite. If tremolite occurs in very tiny fibrous crystals, densely matted and interlocked, it is then known as nephrite (jade). Material containing more or less parallel fibers is somewhat chatoyant and yields weak catseyes. These are sometimes called catseye jades, but have been tested and are actually tremolite or (if more iron-rich) actinolite.

Name

From the Tremola Valley on the south side of St. Gotthard, Switzerland. Hexagonite was so named because it was thought to be a hexagonal mineral when first described.